Biodegradable Wireless Microheaters for Transient Biomedical Implants

Transient electronics show a great potential in the field of bioresorbable medical implants, for applications such as localized drug delivery for wound healing or following a surgical procedure. Once their function is fulfilled, such implants naturally degrade and resorb in the body, which eliminates adverse long-term effects or the need for a secondary surgery to extract the implanted device. Since biodegradable materials are water-soluble, the fabrication of such transient electronic circuits and devices requires special care and needs to rely solely on dry processing steps without exposure to aqueous solutions. A further challenge is the in-vivo powering of medical implants that are only constituted of biodegradable materials. This work describes the design, fabrication and testing of radiofrequency biodegradable magnesium (Mg) microresonators. To this end, an innovative microfabrication process with minimal exposure to aqueous media is developed to fabricate magnesium-based, water soluble electronic components, without the need to fabricate and use fragile stencils. It consists of a novel sequence of only three steps: one physical vapor deposition, one photolithography, and one ion beam etching step. The frequency-selective wireless heating of different resonators is demonstrated.